A series of compounds disclosed in Patent Publication 1 and represented by the following formula:
are compounds derived from microorganisms such as the genus Aureobasidium, and are recognized to have therapeutic effects against fungal infections and immune diseases. The applicant of the present application found that these compounds have a high HCV replication inhibitory activity as determined by a replicon assay (Patent Publication 2). However, since this series of compounds are derived from microorganisms, their synthesis is difficult and had the problem of only being able to synthesize a limited number of peripheral derivatives from their naturally-occurring compounds. The applicant of the present application then developed a method for completely synthesizing these compounds and analogues thereof without using microorganisms (Patent Publication 3). However, this method comprises a large number of steps and did not render an adequate yield. Consequently, there is a need for a process for highly selectively synthesizing a compound having a desired optical activity at high yield in a small number of steps.Patent Publication 1: International Publication WO 98/56755Patent Publication 2: Japanese Patent Application No. 2003-34056Patent Publication 3: Japanese Patent Application No. 2003-272420